Integrated circuits are formed on semiconductor substrates (or wafers). The wafers are then sawn into microelectronic die (or “dice”), or semiconductor chips, with each die carrying a respective integrated circuit. Each semiconductor chip is connected to a package or carrier substrate using either wire bonding or “flip-chip” connections. The packaged chip is then typically mounted to a circuit board, or motherboard, before being installed in a system, such as an electronic or a computing system.
In power integrated circuits, several semiconductor devices with voltage handling capability ranging from low to very high are integrated together. The devices with different characteristics and performance ratings need to be isolated from each other in order to prevent any “cross-talk” leading to malfunction in circuit operation. Thus, device-to-device isolation voltage capability is an important parameter in power integrated circuits.
One of the methods that has been attempted to improve isolation voltage, or voltage handling capability, involves the formation of “isolation rings” around the individual semiconductor devices. Typically, isolation rings utilize a “buried” layer formed below the semiconductor device and a first “well” (or wells) within the substrate that surrounds the device, both including semiconductor material of a dopant type that is opposite to that of the substrate. A second (or isolation well), of the same dopant type as the substrate, is also often formed between the first wells. However, the isolation well is typically formed after the formation of the epitaxial layer over the substrate, and as a result, can not be formed to a depth sufficient to maximize isolation voltage performance.
Accordingly, it is desirable to provide a microelectronic assembly with an improved voltage handling capability between individual semiconductor devices. In addition, it is desirable to provide such an assembly with minimal size and manufacturing costs. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.